Antiglare film

ABSTRACT

The antiglare film of the present invention is provided with an antiglare layer having a haze value in a range from 60% to 95%, an internal haze value in a range from 0.5% to 15.0%, and a standard deviation of luminance distribution of a display in a case where the antiglare film is mounted on a surface of the display in a range from 0 to 10.

TECHNICAL FIELD

The present invention relates to an antiglare film that preventsreflection of external light from being cast onto a surface of adisplay.

BACKGROUND ART

An antiglare film is, for example, a film having an antiglare layerincluding recesses and protrusions formed on a surface thereof bysurface roughening, and such a film is attached to a surface of adisplay to scatter external light and prevent reflection of the externallight from being cast onto the surface of the display.

In addition, when an antiglare film is mounted on a surface of a displayor the like having high definition pixels, light from the display thatpasses through the antiglare film is refracted by the recesses andprotrusions on the surface of the antiglare layer, or pixels of thedisplay may appear to be expanded due to a lens effect from the recessesand protrusions on the surface of the antiglare layer, whereby displayglare may be generated and the image may become difficult to see.

Therefore, measures that intend to suppress the sparkle of a display byforming fine recesses and protrusions on the surface by dispersing, inthe antiglare layer, microparticles having a relatively small particlesize are known as disclosed in Patent Document 1, for example.

CITATION LIST Patent Document

Patent Document 1: JP 2009-109702 A

SUMMARY OF INVENTION Technical Problem

However, in a case where microparticles are merely dispersed in anantiglare layer, the antiglare film could be colored such as beingtinged with a yellow tone for example, and color reproducibility of thedisplay through the antiglare film could be lowered.

Therefore, an object of the present invention is to provide an antiglarefilm that is not easily colored, has favorable antiglare property, andcan suppress sparkle of a display.

Solution to Problem

In order to solve the above problems, an antiglare film according to oneaspect of the present invention is provided with an antiglare layerhaving a haze value in a range from 60% to 95%, an internal haze valuein a range from 0.5% to 15.0%, and a standard deviation of luminancedistribution of a display in a case where the antiglare film is mountedon a surface of the display in a range from 0 to 10.

In the antiglare layer of the antiglare film having the abovementionedconfiguration, with the internal haze value being suppressed to a valuein a range from 0.5% to 15.0%, the haze value is maintained in a rangefrom 60% to 95% by an external haze value.

By configuring the antiglare layer in this manner, even if the internalhaze value of the antiglare layer is not increased, favorable antiglareproperty can be obtained by appropriately roughening the surface of theantiglare layer and adjusting the external haze value. Therefore, forexample, light entering the antiglare film can be suppressed from beingscattered at a wide angle by microparticles in the antiglare layer.Accordingly, wide angle scattering of light of a prescribed wavelengthentering the antiglare film, which leads to coloration of the antiglarefilm (for example, blue light or the like with a short wavelength beingscattered, which leads to coloration of the antiglare film such as beingtinged with yellow) can be prevented.

Here, the value of the standard deviation of the luminance distributionof the display indicates a degree of variation of brightness on thedisplay and is an objective indicator that can be used to quantitativelyevaluate the sparkle of a display. Therefore, with the abovementionedconfiguration, the display sparkle can be more favorably suppressedwhile preventing coloration of the antiglare film by setting the valueof the standard deviation to a value in a range from 0 to 10.

b* value in L*a*b* color system may be set to a value in a range from 0to 10. By setting the b* value in the L*a*b* color system of theantiglare film in this manner, the antiglare film can be favorablyprevented from being tinged with a color tone.

The antiglare layer may include a plurality of resin components and mayhave a co-continuous phase structure formed by phase separation of theplurality of resin components. Because of this, the haze value of theantiglare layer can be appropriately set by forming recesses andprotrusions by a co-continuous phase structure on a surface of theantiglare layer while suppressing the internal haze value of theantiglare layer, whereby the display sparkle can be easily suppressed.

The antiglare layer may include a matrix resin and a plurality ofmicroparticles dispersed in the matrix resin, and a refractive indexdifference between the microparticles and the matrix resin may be avalue in a range from 0 to 0.2.

By setting the refractive index difference between the matrix resin andthe microparticles to a predetermined range in this manner, anddispersing a plurality of microparticles in the matrix resin, thesparkle of the display can be suppressed while ensuring favorableantiglare property, and wide angle scattering of light incident on theantiglare film can be favorably suppressed by the refractive indexdifference between the matrix resin and the microparticles, wherebycoloration of the antiglare film can be prevented.

A ratio G2/G1 of a weight G1 of the matrix resin of the antiglare layerto a total weight G2 of the plurality of microparticles included in theantiglare layer may be a value in a range from 0.07 to 0.20. Because ofthis, the abovementioned antiglare film having an antiglare layer of astructure, in which a plurality of microparticles are dispersed in amatrix resin, can be favorably manufactured.

Advantageous Effects of Invention

According to the present invention, an antiglare film that is not easilycolored, has favorable antiglare property, and can suppress sparkle of adisplay can be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view illustrating a configuration of anantiglare film according to a first embodiment.

FIG. 2 is a diagram illustrating a method of manufacturing an antiglarefilm according to a third embodiment.

FIG. 3 is a schematic view of a sparkle measurement apparatus.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are described below with referenceto the drawings.

First Embodiment

FIG. 1 is a cross-sectional view illustrating a configuration of anantiglare film 1 according to a first embodiment. The antiglare film 1is mounted on a surface of a display 16 a of a display device 16 (seeFIG. 3). The antiglare film 1 is provided with a substrate film 2, anantiglare layer 3, and an adhesive layer 4.

The substrate film 2 is disposed between the display 16 a and theantiglare layer 3, and supports the antiglare layer 3. The adhesivelayer 4 is disposed between the display 16 a and the substrate film 2,and fixes the antiglare film 1 to the surface of the display 16 a. Theadhesive layer 4 is, for example, an optical glue, and is configuredfrom a material that is unlikely to affect optical properties of theantiglare film 1.

The antiglare layer 3 is formed on at least one surface of the substratefilm 2. The antiglare layer 3 imparts antiglare property to theantiglare film 1, and prevents reflection of external light from beingcast onto the surface of the display 16 a by scattering and reflectingthe external light. The antiglare layer 3 functions also as a hard coat(HC) layer that protects the surface of the display 16 a. As an example,the antiglare layer 3 includes a plurality of phase-separable resincomponents.

The haze value of the antiglare layer 3 is set to a value in a rangefrom 60% to 95%, and the internal haze value is set to a value in arange from 0.5% to 15.0%.

The haze value can be appropriately set within the range describedabove, but is more preferably a value in a range from 70% to 85%. Inaddition, the internal haze value can be appropriately set within therange described above, but is more preferably a value in a range from0.5% to 8.0%.

The haze value described in the present embodiment is a value measuredby a method conforming to JIS K7136. The external haze value correspondsto a value obtained by subtracting the internal haze value from the hazevalue. The internal haze value can be measured by coating the antiglarelayer 3 with a resin layer or the like, or affixing a smooth transparentfilm, via a transparent adhesive layer, to the antiglare layer 3 therebyflattening the surface of the antiglare layer 3, and then measuring thehaze value.

In this manner, in the antiglare layer 3 of the antiglare film 1, thehaze value is maintained in a range from 60% to 95% by an external hazevalue, with the internal haze value being suppressed to a value in arange from 0.5% to 15.0%. Furthermore, by configuring the antiglarelayer 3 in this manner, even if the internal haze value of the antiglarelayer 3 is not increased, by appropriately roughening the surface of theantiglare layer and adjusting the external haze value, favorableantiglare property can be obtained. Therefore, for example, lightentering the antiglare film can be suppressed from being scattered at awide angle by microparticles in the antiglare layer. Accordingly, lightof a prescribed wavelength entering the antiglare film 1 can beprevented from being scattered at a wide angle, and from coloring theantiglare film 1 (for example, blue light or the like with a shortwavelength is scattered and the antiglare film is colored to be tingedwith yellow, for instance).

Moreover, in the antiglare film 1, b* value in L*a*b* color system isset to a value in a range from 0 to 10. By setting the b* value in theL*a*b* color system of the antiglare film 1 in this manner, theantiglare film 1 is favorably prevented from being tinged with a colortone.

Furthermore, as described in detail below, the antiglare layer 3 mayinclude a plurality of resin components and may have a co-continuousphase structure formed by phase separation of the plurality of resincomponents. With this, the haze value of the antiglare layer 3 can beappropriately set by forming recesses and protrusions by theco-continuous phase structure on a surface of the antiglare layer 3while suppressing the internal haze value of the antiglare layer 3,whereby sparkle of the display 16 a can be easily suppressed.

The standard deviation (also referred to as a sparkle value below) ofthe luminance distribution of the display 16 a in a state where theantiglare film 1 is mounted on the surface of the display 16 a, is setto a value in a range from 0 to 10.

Here, the value of the standard deviation of the luminance distributionof the display 16 a indicates a degree of variation of brightness on thedisplay 16 a and is an objective indicator that can be used toquantitatively evaluate the sparkle of the display 16 a. Therefore,sparkle of the display 16 a can be more favorably suppressed whilepreventing coloration of the antiglare film 1 by setting the value ofthe standard deviation to a value in a range from 0 to 10. Specificexamples of the substrate film 2 and the antiglare layer 3 are describedbelow.

Examples of materials of the substrate film 2 include glass, ceramic,and resin. As the resin, a resin similar to the material of theantiglare layer 3 can be used. Preferred materials of the substrate film2 include transparent polymers, such as, for example, cellulosederivatives (such as cellulose triacetate (TAC), cellulose diacetate,and other such cellulose acetates), polyester resins (such aspolyethylene terephthalate (PET), polyethylene naphthalate (PEN),polybutylene terephthalate (PBT), and polyarylate-based resins),polysulfone resins (such as polysulfone and polyethersulfone (PES)),polyether ketone based resins (such as polyetherketone (PEK) andpolyether ether ketone (PEEK)), polycarbonate-based resins (PC),polyolefin-based resins (such as polyethylene and polypropylene), cyclicpolyolefin-based resins (such as “ARTON” (registered trade name) filmavailable from JSR Corporation and “ZEONEX” (registered trade name) filmavailable from Zeon Corporation), halogen-containing resins (such aspolyvinylidene chloride), (meth) acrylic resins, styrene-based resins(such as polystyrene), and vinyl acetate or vinyl alcohol-based resins(such as polyvinyl alcohol).

The substrate film 2 may be uniaxially or biaxially stretched, but ispreferably optically isotropic and has a low refractive index. Examplesof the optically isotropic substrate film 2 include unstretched films.

The thickness dimension of the substrate film 2 can be appropriatelyset, but for example, is desirably a value in a range from 5 μm to 2000μm, more desirably a value in a range from 15 μm to 1000 μm, and stillmore desirably a value in a range from 20 μm to 500 μm.

Structure of Antiglare Layer

The antiglare layer 3 of the first embodiment has a phase separationstructure of a plurality of resin components. As an example, theantiglare layer 3 has on the surface thereof a plurality of long, narrow(string-like or linear) protrusions formed by the phase separationstructure of a plurality of resin components. The long, narrowprotrusions are branched and form a co-continuous phase structure in adense state.

The antiglare layer 3 manifests antiglare property by the plurality oflong, narrow protrusions and recesses located between adjacent long,narrow protrusions. By providing the antiglare layer 3 like this, theantiglare film 1 has excellent balance between the haze value andtransmission image clarity (image clarity). The long, narrow protrusionsare formed in a roughly net-like shape, whereby the surface of theantiglare layer 3 has a net-like structure, or in other words, aplurality of irregular loop structures that are continuous or partiallymissing.

With the formation of the abovementioned structure at the surface of theantiglare layer 3, the formation of protrusions in a lens shape(sea-island shape) is prevented. Thus, the refraction of light, passingthrough the antiglare layer 3 from the display 16 a, by the recesses andprotrusions of the surface of the antiglare layer 3, and expandedappearance of pixels of the display 16 a due to a lens effect from therecesses and protrusions of the surface of the antiglare layer 3 areprevented, and the sparkle of the display 16 a is suppressed. As aresult, even when the antiglare film 1 is mounted on the display 16 ahaving high definition pixels, the sparkle of the display 16 a can besuppressed to a high degree while ensuring antiglare property, and textand image blurring can be suppressed.

Note that the plurality of long, narrow protrusions may be mutuallyindependent or may be connected. As described below, the phaseseparation structure of the antiglare layer 3 is formed by spinodaldecomposition (wet spinodal decomposition) from the liquid phase using asolution that is a raw material of the antiglare layer 3. For details ofthe antiglare layer 3, reference can be made to the description in JP2012-231496, for example.

Material of Antiglare Layer

It is sufficient that the plurality of resin components included in theantiglare layer 3 be phase-separable, but from the perspective ofobtaining an antiglare layer 3 on which long, narrow protrusions areformed and which has high scratch resistance, the plurality of resincomponents preferably include a polymer and a curable resin.

Examples of the polymer contained in the antiglare layer 3 includethermoplastic resins. Examples of the thermoplastic resins includestyrene-based resins, (meth)acrylate polymers, organic acid vinyl esterresins, vinyl ester resins, halogen-containing resins, olefin-basedresins (including alicyclic olefin-based resins), polycarbonate resins,polyester resins, polyamide resins, thermoplastic polyurethane resins,polysulfone-based resins (such as polyether sulfone and polysulfone),polyphenylene ether-based resins (such as a polymer of 2,6-xylenol),cellulose derivatives (such as cellulose esters, cellulose carbamates,and cellulose ethers), silicone resins (such as polydimethylsiloxane andpolymethylphenylsiloxane), and rubbers or elastomers (such as,polybutadiene, polyisoprene, and other diene-based rubbers,styrene-butadiene copolymers, acrylonitrile-butadiene copolymers,acrylic rubber, urethane rubber, and silicone rubber). Thesethermoplastic resins can be used alone or in a combination of two ormore.

Examples of the polymer include polymers having a functional group thatparticipates in a curing reaction, or polymers having a functional groupthat reacts with a curable compound. The polymer may have a functionalgroup in the main chain or side chain.

Examples of the functional group include condensable groups, reactivegroups (for example, a hydroxyl group, an acid anhydride group, acarboxyl group, an amino group or an imino group, an epoxy group, aglycidyl group, or an isocyanate group), and polymerizable groups (forexample, C₂₋₆ alkenyl groups such as vinyl, propenyl, isopropenyl,butenyl, and allyl groups, C₂₋₆ alkynyl group such as ethynyl, propynyl,and butynyl groups, C₂₋₆ alkenylidene groups such as a vinylidene group,or a group (such as a (meth)acryloyl group) having a polymerizable groupthereof). Of these functional groups, a polymerizable group ispreferable.

Furthermore, the antiglare layer 3 may include a plurality of types ofpolymers. Each of these polymers may be phase separable by spinodaldecomposition from the liquid phase, and may be mutually immiscible. Thecombination of a first polymer and a second polymer included in theplurality of types of polymers is not particularly limited, and polymerswhich are mutually immiscible near a processing temperature can be used.

For example, when the first polymer is a styrene-based resin (such aspolystyrene or a styrene-acrylonitrile copolymer), the second polymermay be, for example, a cellulose derivative (for example, a celluloseester such as cellulose acetate propionate), a (meth) acrylic resin(such as polymethyl methacrylate), an alicyclic olefin resin (such as apolymer containing norbornene as a monomer), a polycarbonate-basedresin, or a polyester-based resin (such as a poly C₂₋₄ alkylenearylate-based copolyester).

Also, for example, when the first polymer is a cellulose derivative (forexample, a cellulose ester such as cellulose acetate propionate), thesecond polymer may be, for example, a styrene-based resin (such aspolystyrene or a styrene-acrylonitrile copolymer), a (meth) acrylicresin, an alicyclic olefin resin (such as a polymer containingnorbornene as a monomer), a polycarbonate-based resin, or apolyester-based resin (such as a poly C₂₋₄ alkylene arylate-basedcopolyesters).

The plurality of types of polymers may include at least a celluloseester (for example, a cellulose C₂₋₄ alkyl carboxylate such as cellulosediacetate, cellulose triacetate, cellulose acetate propionate, orcellulose acetate butyrate).

Here, when manufacturing the antiglare layer 3, the phase separationstructure of the antiglare layer 3 is fixed by curing of a precursor ofthe curable resin contained in the plurality of resin components by, forexample, activate energy rays (such as ultraviolet light or electronbeams) or heat. Additionally, scratch resistance and durability areimparted to the antiglare layer 3 by such a curable resin.

From the perspective of obtaining scratch resistance of the antiglarelayer 3, at least one polymer included in the plurality of types ofpolymers is preferably a polymer having, in a side chain, a functionalgroup that can react with a curable resin precursor. The polymer thatforms the phase separation structure may include a thermoplastic resinor other polymer in addition to the two mutually immiscible polymersdescribed above. A weight ratio M1/M2 of a weight M1 of the firstpolymer to a weight M2 of the second polymer, and the glass transitiontemperature of the polymers can be set as appropriate.

Examples of the curable resin precursor include curable compounds havinga functional group that undergoes a reaction by heat or active energyrays (such as ultraviolet light or electron beams) for example, andundergoes curing or crosslinking through this functional group therebyforming a resin (in particular, a cured or crosslinked resin).

Examples of such a compound include a thermosetting compound or athermosetting resin (a low molecular weight compound (such as forexample, an epoxy resin, an unsaturated polyester resin, a urethaneresin, and a silicone resin) having, for example, an epoxy group, apolymerizable group, an isocyanate group, an alkoxysilyl group, or asilanol group), and a photocurable (ionizing radiation curable) compoundthat can be cured by ultraviolet light, electron beams or the like (suchas photocurable monomers, oligomers and other such UV curablecompounds).

Examples of preferable curable resin precursors include photocurablecompounds that are cured in a short period of time by, for example,ultraviolet light or electron beams. Of these, UV curable compounds areparticularly practical. In addition, to improve resistance such asscratch resistance, the photocurable compound preferably has 2 or more(preferably from 2 to 15, and more preferably from 4 to 10)polymerizable unsaturated bonds per molecule. Specifically, thephotocurable compound is preferably epoxy (meth) acrylate, urethane(meth) acrylate, polyester (meth) acrylate, silicone (meth) acrylate, ora multifunctional monomer having at least two polymerizable unsaturatedbonds.

The curable resin precursor may include, according to the type thereof,a curing agent. For example, the thermosetting resin precursor mayinclude a curing agent such as amines and polyvalent carboxylic acids,and the photocurable resin precursor may include a photopolymerizationinitiator. Examples of the photopolymerization initiator includecommonly used components such as acetophenones or propiophenones,benzyls, benzoins, benzophenones, thioxanthones, and acylphosphineoxides.

Furthermore, the curable resin precursor may include a curingaccelerator. For example, the photocurable resin precursor may include aphotocuring accelerator, for example, a tertiary amine (such asdialkylaminobenzoate), and a phosphine-based photopolymerizationaccelerator.

In a manufacturing process of the antiglare layer 3, at least twocomponents of the curable resin precursor and the polymer contained inthe solution that serves as the raw material of the antiglare layer 3are used as a combination that implements mutual phase separation nearthe processing temperature. Examples of the combination that implementsphase separation include (a) a combination in which a plurality of typesof polymers are immiscible and phase separate; (b) a combination inwhich a polymer and a curable resin precursor are immiscible and phaseseparate, or (c) a combination in which a plurality of curable resinprecursors themselves are immiscible and phase separate. Of thesecombinations, ordinarily the combination (a) of a plurality of types ofpolymers, and the combination (b) of a polymer and a curable resinprecursor are used, and the combination of (a) a plurality of types ofpolymers is preferable.

Typically, the refractive index of the polymer and the refractive indexof the cured resin or crosslinked resin produced by curing the curableresin precursor mutually differ. Moreover, typically, the refractiveindexes of the plurality of types of polymers (the first polymer and thesecond polymer) also mutually differ. A difference between therefractive index of the polymer and refractive index of the cured resinor crosslinked resin, and the difference between the refractive indexesof the plurality of types of polymers (the first polymer and the secondpolymer) are, for example, preferably a value in a range from 0 to 0.04,and more preferably a value in a range from 0 to 0.02.

The antiglare layer 3 may include a plurality of microparticles(fillers) dispersed in a matrix resin. The microparticles may be organicmicroparticles and/or inorganic microparticles, and the plurality ofmicroparticles may include a plurality of types of microparticles.

Examples of the organic microparticles include crosslinked acrylicparticles and crosslinked styrene particles. Examples of the inorganicmicroparticles include silica particles and alumina particles. Inaddition, the refractive index difference between the microparticles andthe matrix resin included in the antiglare layer 3 can be set to a valueranging from 0 to 0.2, as an example. This refractive index differenceis more desirably a value in a range from 0 to 0.15, and still morepreferably a value in a range from 0 to 0.07.

An average particle size of the microparticles is not particularlylimited, and for example, can be set to a value in a range from 0.5 μmto 5.0 μm. The average particle size is more preferably a value in arange from 0.5 μm to 4.0 μm, and still more preferably a value in arange from 1.0 μm to 3.0 μm.

Note that the average particle size referred to here is the 50% volumeaverage particle size with regards to the Coulter counter method (thesame applies to the average particle size referred to below). Themicroparticles may be solid or hollow. It should be noted that if theaverage particle size of the microparticles is too small, antiglareproperty will be difficult to achieve, and if the average particle sizeis too large, the sparkle of the display could be large.

The thickness dimension of the antiglare layer 3 can be set asappropriate, but is, for example, preferably a value in a range from 0.3μm to 20 μm, more preferably a value in a range from 1 μm to 15 μm, andstill more preferably a value in a range from 1 μm to 10 μm. Ordinarily,the thickness dimension is set to a value in a range from 2 μm to 10 μm(in particular, a value in a range from 3 μm to 7 μm).

Note that the antiglare film can also be configured without thesubstrate film 2, but in this case, the thickness dimension of theantiglare layer 3 is preferably a value in a range from 1 μm to 100 μm,and more preferably a value in a range from 3 μm to 50 μm.

The antiglare layer 3 may contain commonly used additives within a rangethat does not impair the optical properties, and examples thereofinclude organic or inorganic particles, a stabilizer (such as anantioxidant and a UV absorbers), surfactants, water-soluble polymers,fillers, crosslinking agents, coupling agents, colorants, flameretardants, lubricants, waxes, preservatives, viscosity modifiers,thickeners, leveling agents, and antifoaming agents.

The method of manufacturing the antiglare film according to the firstembodiment includes, by way of example, a preparation step of preparinga solution that serves as a raw material of the antiglare layer 3(hereinafter, also simply referred to as a “solution”), a formation stepof coating a surface of a predetermined support (the substrate film 2 inthe present embodiment) with the solution prepared in the preparationstep, evaporating the solvent in the solution, and forming a phaseseparation structure by spinodal decomposition from a liquid phase, anda curing step of curing a curable resin precursor after the formationstep.

Preparation Step

In the preparation step, a solution containing a solvent and a resincomposition for configuring the antiglare layer 3 is prepared. Thesolvent can be selected according to the type and solubility of thecurable resin precursor and polymer contained in the above-describedantiglare layer 3. The solvent is preferably a solvent that canuniformly dissolve at least solid content (the plurality of types ofpolymers and the curable resin precursor, a reaction initiator, andother additives).

Examples of the solvent include ketones (such as acetone, methyl ethylketone, methyl isobutyl ketone, and cyclohexanone), ethers (such asdioxane and tetrahydrofuran), aliphatic hydrocarbons (such as hexane),alicyclic hydrocarbons (such as cyclohexane), aromatic hydrocarbons(such as toluene and xylene), halogenated carbons (such asdichloromethane and dichloroethane), esters (such as methyl acetate,ethyl acetate, and butyl acetate), water, alcohols (such as ethanol,isopropanol, butanol, and cyclohexanol), cellosolves (such as methylcellosolve and ethyl cellosolve), cellosolve acetates, sulfoxides (suchas dimethyl sulfoxide), and amides (such as dimethylformamide anddimethylacetamide). In addition, the solvent may be a mixed solvent.

A composition containing the thermoplastic resin, a photocurablecompound, a photopolymerization initiator, the thermoplastic resin, anda photocurable compound is desirable as the resin composition.Alternatively, a composition containing the plurality of types ofmutually immiscible polymers, a photocurable compound, and aphotopolymerization initiator is desirable as the resin composition.

The concentration of a solute (polymer and curable resin precursor,reaction initiator, and other additives) in the solution can be adjustedin a range in which phase separation of the plurality of resincomponents occurs, and in which the flow extensibility, coatingproperties and such of the solution are not impaired.

Here, a haze value and an internal haze value of the antiglare layer 3,b* value in L*a*b* color system of the antiglare film 1, and a value(sparkle value) of the standard deviation of the luminance distributionof the display 16 a having the antiglare film 1 mounted on the surfacethereof may vary, depending on the combination of resin compositions inthe solution or the weight ratio, or the execution conditions of thepreparation step, the formation step, and the curing step. Therefore, anantiglare film having targeted physical properties can be obtained bychanging each of the conditions to form the antiglare layer, andmeasuring and ascertaining in advance the physical properties of theobtained antiglare layer.

Formation Step

In the formation step, the solution prepared in the preparation step iscast onto the surface of the support (here, as an example, the substratefilm 2) to be coated thereon. Examples of a method for casting or amethod for coating with the solution include commonly used methodsusing, for instance, spraying, a spinner, a roll coater, an air knifecoater, a blade coater, a rod coater, a reverse coater, a bar coater, acomma coater, dipping, a dip squeeze coater, a die coater, a gravurecoater, a micro gravure coater, and a silk screen coater.

The solvent is evaporated and removed by drying from the solution castor coated onto the surface of the support. Phase separation throughspinodal decomposition from the liquid phase of the plurality of resincomponents occurs in association with concentration of the solution inthis evaporation process, and a phase separation structure with arelatively regular interphase distance (pitch or mesh diameter) isformed. The co-continuous phase structure of the long, narrowprotrusions can be formed by setting formulation and drying conditionssuch that the melt flowability of the resin component after solventevaporation becomes relatively high.

From the perspective of easily forming the long, narrow protrusions onthe surface of the antiglare layer 3, the solvent is preferablyevaporated by heating and drying. Note that in a case where the dryingtemperature is too low or the drying time is too short, an amount ofheat that is imparted to the resin component will be insufficient, andthe melt flowability of the resin component may be reduced, which maymake it difficult to form long, narrow protrusions.

On the other hand, in a case where the drying temperature is too high orthe drying time is too long, once formed, the long, narrow protrusionsmay flow, leading to a decrease in height, but the structure of thelong, narrow protrusions is maintained. Therefore, the dryingtemperature and drying time can be used as means for adjusting antiglareproperty and slipperiness of the antiglare layer 3 by changing theheight of the long, narrow protrusions. Furthermore, in the formationstep, a co-continuous phase structure, in which the phase separationstructure is connected, can be formed by increasing the evaporationtemperature of the solvent or using a component having a low viscosityfor the resin component.

When the co-continuous phase structure is formed and roughening occursin association with the progression of phase separation due to spinodaldecomposition from the liquid phase of the plurality of resincomponents, the continuous phase becomes discontinuous, and a dropletphase structure (sea-island structure of an independent phase having ashape such as spherical, perfectly spherical, disc-like, or ellipsoidal)is formed. Here, depending on the degree of phase separation, anintermediate structure between the co-continuous phase structure and thedroplet phase structure (that is, a phase structure in a process oftransitioning from the co-continuous phase to the droplet phase) canalso be formed. After the solvent has been removed, a layer with finerecesses and protrusions is formed on the surface.

By forming fine recesses and protrusions on the layer surface by phaseseparation, the haze value of the antiglare layer 3 can be adjusted evenwithout dispersing microparticles in the antiglare layer 3. Moreover,because microparticles need not be dispersed in the antiglare layer 3,the haze value of the antiglare layer 3 can be more easily adjustedwhile suppressing the internal haze value than the external haze value.Note that the antiglare layer 3 containing microparticles can also beformed by adding microparticles to the solution in the preparation step,but in this case, when the refractive index difference between thematrix resin and the microparticles in the antiglare layer 3 is large,there is a chance that the antiglare layer 3 could be colored, thereforeattention has to be paid.

Curing Step

In the curing step, the curable resin precursor in the solution iscured, whereby the phase separation structure formed in the formationstep is fixed and the antiglare layer 3 is formed. Curing of the curableresin precursor is performed by heating or irradiation with an activeenergy ray, or by a combination of these methods, depending on the typeof curable resin precursor. The active energy ray to be irradiated isselected according to the type of photocurable components or the like.

The irradiation with an active energy ray may be performed in an inertgas atmosphere. When the active energy ray is ultraviolet light,examples of light sources that can be used include a far-ultravioletlight lamp, a low-pressure mercury lamp, a high-pressure mercury lamp,an ultrahigh-pressure mercury lamp, a halogen lamp, and a laser lightsource (light source such as a helium-cadmium laser and an excimerlaser).

Note that when forming the adhesive layer 4, after a solution containingan adhesive component is prepared, the adhesive layer 4 can be formed bycoating another surface of the substrate film 2 with the solution andthen drying the coated surface by a commonly used method such as forexample, the casting method or the coating method described above in theformation step.

By implementing each of the above steps, the antiglare film 1 of thefirst embodiment is produced. Note that when a support havingreleasability is used as the support, the antiglare layer 3 is peeledfrom the support, whereby an antiglare film constituted only of theantiglare layer 3 can be obtained. Furthermore, when a non-releasablesupport (preferably a transparent support such as the substrate film 2)is used as the support, the antiglare film 1 having a laminatedstructure of the support (substrate film 2) and the antiglare layer 3can be obtained.

Here, as a method for suppressing the sparkle of the display 16 a, it isconceivable, for example, to reduce the recesses and protrusions of thesurface of the antiglare layer, but the antiglare property of theantiglare film may decrease. However, antiglare property can be improvedwhile suppressing the sparkle of the display by not only reducing therecesses and protrusions of the antiglare layer, but also increasinginclination of the recesses and protrusions of the antiglare layer tomake recesses and protrusions steeper, and increasing the number ofrecesses and protrusions.

Such recesses and protrusions can be formed in the antiglare layer bythe spinodal decomposition described above in the first embodiment, butsuch recesses and protrusions can also be formed in the antiglare layerby other methods. For example, even when a plurality of microparticlesare used to form the recesses and protrusions in the surface of theantiglare layer as in a second embodiment, suitable aggregation of themicroparticles can be caused by material selection that allows therepulsive interaction between the microparticles and resins and solventsother than the particles to be strong when forming the antiglare layer,whereby a distributed structure of steep recesses and protrusions havinga high number density can be formed on the antiglare layer. Hereinafter,the antiglare layer of other embodiments will be described focusing ondifferences from the first embodiment.

Second Embodiment

The antiglare layer of the antiglare film according to a secondembodiment includes a matrix resin and a plurality of microparticlesdispersed in the matrix resin. The microparticles are formed in aperfectly spherical shape, but the shape of the microparticles is notlimited thereto, and may be formed in a substantially spherical orellipsoidal shape. In addition, the microparticles are formed in a solidform, but may also be formed so as to be hollow. When the microparticlesare hollow, the hollow part of the microparticles may be filled with airor another gas. In the antiglare layer, each type of microparticles maybe dispersed as a primary particle, or a plurality of secondaryparticles, formed by aggregating a plurality of microparticles, may bedispersed.

The refractive index difference between the matrix resin and themicroparticles is set to a value in a range from 0 to 0.2. Thisrefractive index difference is more preferably a value in a range from 0to 0.15, and still more preferably a value in a range from 0 to 0.07.

The microparticles have an average particle size that is set to a valuein a range from 0.5 μm to 5.0 μm. The average particle size of themicroparticles is more preferably a value in a range from 0.5 μm to 4.0μm, and still more preferably a value in a range from 1.0 μm to 3.0 μm.

In addition, variation in particle size of the microparticles ispreferably small, and for example, in the particle size distribution ofthe microparticles contained in the antiglare layer, a 50 wt. % orgreater average particle size of microparticles included in theantiglare layer is preferably confined to a variation within 1.0 μm.

In this manner, uniform and moderate recesses and protrusions are formedin the surface of the antiglare layer by microparticles having arelatively uniform particle size and an average particle size, which iswithin the aforementioned range. As a result, the sparkle of the display16 a can be suppressed while ensuring antiglare property. Moreover, bysetting the refractive index difference between the matrix resin and themicroparticles to the range described above, wide angle scattering oflight of a prescribed wavelength entering the antiglare film, whichleads to coloration of the antiglare film, can be prevented.

A ratio between the weight of the matrix resin and the total weight ofthe plurality of microparticles in the antiglare layer can be set asappropriate. In the present embodiment, a ratio G2/G1 of the weight G1of the matrix resin of the antiglare layer to a total weight G2 of theplurality of microparticles included in the antiglare layer is set to avalue in a range from 0.07 to 0.20. The ratio G2/G1 is preferably avalue in a range from 0.1 to 0.20, and more preferably a value in arange from 0.12 to 0.2.

The microparticles dispersed in the matrix resin may be either inorganicor organic, but preferably have favorable transparency. Examples of theorganic microparticles include plastic beads. Examples of the plasticbeads include styrene beads (refractive index of 1.59), melamine beads(refractive index of 1.57), acrylic beads (refractive index of 1.49),acrylic-styrene beads (refractive index of 1.54), polycarbonate beads,and polyethylene beads. The styrene beads may be cross-linked styrenebeads, and the acrylic beads may be cross-linked acrylic beads. Theplastic beads desirably have on the surface thereof a hydrophobic group.Examples of such plastic beads include styrene beads.

Examples of the matrix resin include at least any of a photocurableresin that is cured by an active energy ray, a solvent-drying resin thatcures through drying of a solvent added during coating, and athermosetting resin.

Examples of photocurable resins include those having an acrylate-basedfunctional group, such as, for example, relatively low molecular weightpolyester resins, polyether resins, acrylic resins, epoxy resins,urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins,polythiol polyene resins; oligomers such as (meth) acrylates ofpolyfunctional compounds such as polyhydric alcohols; prepolymers; andreactive diluents.

Specific examples of these include monofunctional monomers such as ethyl(meth) acrylate, ethylhexyl (meth) acrylate, styrene, methyl styrene,and N-vinylpyrrolidone, as well as multifunctional monomers such as, forexample, polymethylol propane tri(meth) acrylate, hexanediol (meth)acrylate, tripropylene glycol di(meth) acrylate, diethylene glycoldi(meth) acrylate, pentaerythritol tri(meth) acrylate, dipentaerythritolhexa(meth) acrylate, 1,6-hexanediol di(meth) acrylate, and neopentylglycol di(meth) acrylate.

When the photocurable resin is a UV curable resin, use of aphotopolymerization initiator is preferable. Examples ofphotopolymerization initiators include acetophenones, benzophenones,Michler's benzoyl benzoate, α-amyloxime ester, tetramethylthiurammonosulfide, and thioxanthones. Furthermore, a photosensitizer ispreferably mixed with the photocurable resin for use. Examples of thephotosensitizer include n-butylamine, triethylamine, andpoly-n-butylphosphine.

Examples of the solvent-drying resin include known thermoplastic resins.Examples of the thermoplastic resin include styrene-based resins, (meth)acrylic resins, vinyl acetate resins, vinyl ether resins,halogen-containing resins, alicyclic olefin resins, polycarbonateresins, polyester resins, polyamide resins, cellulose derivatives,silicone resins, and rubbers or elastomers. The solvent-drying resin ispreferably a resin that is soluble in an organic solvent and, inparticular, is preferably a resin that excels in moldability, filmformability, transparency, and weather resistance. Examples of such asolvent-drying resin include styrene-based resins, (meth) acrylicresins, alicyclic olefin resins, polyester resins, and cellulosederivatives (such as cellulose esters).

Here, when the material of the substrate film 2 is a cellulosic resinsuch as triacetyl cellulose (TAC), a cellulosic resin can be exemplifiedas a thermoplastic resin used in a solvent-drying resin. Examples ofthis cellulosic resin include cellulose derivatives such asnitrocellulose, acetyl cellulose, acetylbutyl cellulose, ethylcellulose, methyl cellulose, cellulose acetate propionate, and ethylhydroxyethyl cellulose. By using a cellulosic resin as a solvent-dryingresin, the substrate film 2 and the antiglare layer 3 can be tightlyjoined with favorable adherence, and the antiglare film 1 havingexcellent transparency can be obtained.

Furthermore, other examples of the solvent-drying resin include vinylresins, acetal resins, acrylic resins, polystyrene resins, polyamideresins, and polycarbonate resins.

Examples of thermosetting resins include phenolic resins, urea resins,diallyl phthalate resins, melamine resins, guanamine resins, unsaturatedpolyester resins, polyurethane resins, epoxy resins, amino alkyd resins,melamine-urea co-condensed resins, silicon resins, and polysiloxaneresins. When a thermosetting resin is used as the matrix resin, at leastone of a crosslinking agent, a polymerization initiator or other suchcuring agent, a polymerization accelerator, a solvent, and a viscosityadjusting agent may be used in combination.

A method of manufacturing an antiglare film according to the secondembodiment includes, by way of example, a preparation step of preparinga solution that serves as a raw material of the antiglare layer 3, acoating step of coating a surface of a predetermined support (thesubstrate film 2 in the present embodiment) with the solution preparedin the preparation step, and a curing step of curing the resin in thecoated solution.

Preparation Step

In the preparation step, a solution containing a solvent, a resincomposition for configuring the antiglare layer, and microparticles isprepared. Examples of the solvent include at least any of alcohols (suchas isopropyl alcohol, methanol, and ethanol), ketones (such as methylethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone),esters (such as methyl acetate, ethyl acetate, and butyl acetate),halogenated hydrocarbons, and aromatic hydrocarbons (such as toluene andxylene). A known leveling agent may be further added to the solution.Excellent scratch resistance can be imparted to the antiglare layer byusing, for example, a fluorine-based or silicone-based leveling agent.

Coating and Curing Step

In the coating step, the solution prepared in the preparation step iscast onto the surface of the support (here, as an example, the substratefilm 2) by a method similar to that of the first embodiment to be orcoated thereon. The solvent is evaporated and removed by drying from thesolution that was cast or coated onto the surface of the support.

In a case where the matrix resin is a photocurable resin, a curing stepof curing by, for example, ultraviolet light or electron beams, isperformed after the coating step. Examples of the ultraviolet lightsource include light sources of various types of mercury lamps,ultraviolet carbon arc lamps, black lights, and metal halide lamps. Thewavelength range of the ultraviolet light can be, for example, awavelength ranging from 190 nm to 380 nm.

Examples of the electron beam source include known electron beamaccelerators. Specific examples include various electron beamaccelerators such as a Van de Graaff accelerator, a Cockcroft-Waltonaccelerator, a resonant transformer type accelerator, an insulating coretransformer type accelerator, a linear accelerator, a Dynamitron typeaccelerator, and a high frequency type accelerator.

The positions of the microparticles in the matrix resin is fixed bycuring the matrix resin contained in the solution. As a result, aplurality of microparticles are dispersed in the matrix resin, and anantiglare layer having a structure, in which recesses and protrusionsare formed by microparticles in the surface is formed.

According to the antiglare film of the second embodiment, by setting therefractive index difference between the matrix resin and themicroparticles to a predetermined range, and dispersing a plurality ofmicroparticles in the matrix resin, the sparkle of the display 16 a canbe suppressed while ensuring favorable antiglare property, wide anglescattering of light incident on the antiglare film can be favorablysuppressed, and coloration of the antiglare film can be prevented by therefractive index difference between the matrix resin and themicroparticles.

In addition, since the ratio G2/G1 is set to a value in a range from0.07 to 0.15, an antiglare film having an antiglare layer with astructure, in which a plurality of microparticles is dispersed in thematrix resin, can be favorably manufactured.

Third Embodiment

An antiglare layer 33 of an antiglare film according to a thirdembodiment has a structure in which a concave-convex shape is formed ona surface on a side opposite the substrate film side. The antiglarelayer 33 is constituted of a resin layer. As an example, this resinlayer is configured from a material similar to that of the matrix resinof the second embodiment.

Specifically, the antiglare film according to the third embodiment ismanufactured by forming, on a substrate film, a coating layer thatincludes a curable resin, followed by shaping a surface of the coatinglayer into a concave-convex shape, and then curing the coating layer.FIG. 2 is a diagram illustrating a method of manufacturing the antiglarefilm according to the third embodiment. In the example of FIG. 2, a UVcurable resin is used as the curable resin.

As illustrated in FIG. 2, in this manufacturing method, a substrate film20 a is unwound from an unwinding roll (not illustrated) and conveyed ina predetermined direction. A downstream end portion of the substratefilm 20 a in the conveyance direction is inserted through a nip point N1between a pair of rolls 21, 22.

A UV curable resin precursor is adhered to a circumferential surface ofthe roll 22 from a circumferential surface of a roll 23 that is axiallysupported adjacent to the roll 22. As the substrate film 20 a passesthrough the nip point N1, the UV curable resin precursor is coated ontoone surface of the substrate film 20 a.

The layer (hereinafter, referred to as a coating layer) of the UVcurable resin precursor coated onto the substrate film 20 a is pressedtogether with the substrate film 20 a at the nip point between the rolls21, 24. The roll 24 is a roll-shaped mold (embossing roll) having finerecesses and protrusions formed on the circumferential surface, andtransfers the concave-convex shape to the surface of the coating layeras the film passes through the nip point N2 between the rolls 21, 24.

The coating layer having the concave-convex shape transferred to thesurface by the roll 24 is cured by ultraviolet light irradiated from anultraviolet lamp 26 provided below the rolls 21, 24. As a result, theantiglare layer 33 is formed. The antiglare film produced in this manneris released from the roll 24 by a roll 25 that is axially supportedadjacent to the roll 24, and is conveyed in a predetermined direction.

Here, the recesses and protrusions on the surface of the roll 24 areformed by striking the surface with blast particles having apredetermined particle size by a blasting method, and the concave-convexshape formed in the coating layer of the antiglare film can be adjustedby adjusting the blast particle size.

As the substrate film 20 a, a PET (polyethylene terephthalate) film, aTAC (triacetyl cellulose) film, a COP (cycloolefin polymer) film, anacrylic resin film, or a polycarbonate resin film can be preferablyused.

Thus, the method of fabricating the antiglare film according to thethird embodiment includes a step (a) of coating a substrate film with acurable resin precursor, a step (b) of striking the surface of a rollwith blast particles to fabricate a roll-shaped mold having aconcave-convex shape on the surface, a step (c) of using thisroll-shaped mold to transfer the concave-convex shape to the surface ofthe curable resin precursor coated onto the substrate film, and a step(d) of curing the curable resin precursor to which the concave-convexshape was transferred, thereby forming an antiglare layer having aconcave-convex shape on the surface.

An average particle size of the blast particles used in step (b) can beset as appropriate, and as an example, can be set to a value in a rangefrom 10 μm to 50 μm. The average particle size of the blast particles ispreferably a value in a range from 20 μm to 45 μm, is more preferably avalue in a range from 30 μm to 40 μm. As a result, an antiglare layer 33having a concave-convex shape formed on the surface is obtained.

Note that a mold used in the third embodiment may be a type other than aroll type mold, and for example, may be a plate-like mold (embossingplate). Furthermore, after the coating layer (resin layer) is formed onone surface of the substrate film, the surface of the coating layer maybe shaped by the mold, and the coating layer may be cured therebyforming the antiglare layer 33. Furthermore, in the example describedabove, the coating layer was cured after shaping the surface of thecoating layer, but the shaping and curing of the coating layer may beperformed simultaneously.

The material of the mold can be, for example, metal, plastic, or wood. Acoating may be provided on a contact surface of the mold that contactsthe coating layer for durability (wear resistance) improvement of themold. The material of blast particles can be, for example, metal,silica, alumina, or glass. The blast particles can strike the surface ofthe mold by pressure of a gas or liquid for example. In addition, whenthe curable resin precursor is an electron beam curing type, an electronbeam source, such as an electron beam accelerator, can be used in placeof the ultraviolet lamp 26, and when the curable resin precursor is heatcurable, a heating source, such as a heater, can be used in place of theultraviolet lamp 26.

With the antiglare film of the third embodiment, microparticles need notbe dispersed in the antiglare layer 33, and therefore light incident onthe antiglare film is scattered in a wide angle due to the refractiveindex difference between the matrix resin and the microparticles in theantiglare layer, whereby coloration of the antiglare film can befavorably prevented.

Note that the antiglare layer of the antiglare film according to theembodiments described above may further have an upper layer disposed ona surface on a side opposite the substrate film 2 side. By providingthis upper layer, the external haze of the antiglare layer can be easilyadjusted, and the antiglare film can be easily protected from theoutside.

The thickness of the upper layer can be set as appropriate, and forexample, can be set to a value in a range from 10 nm to 2 μm. Thethickness of the upper layer is more preferably a value in a range from50 nm to 1 μm, and still more preferably a value in a range from 70 nmto 500 nm. A sparkle measurement apparatus and a sparkle evaluationmethod for inspecting and evaluating the antiglare film of theembodiments described above are described, in order, below.

Sparkle Measurement Apparatus

FIG. 3 is a schematic view of a sparkle measurement apparatus 10. Thesparkle measurement apparatus 10 is a device for evaluating the sparkleof the display 16 a of the display device 16 to which a film such as anantiglare film 1 is mounted on a surface, and the sparkle measurementapparatus 10 is provided with a housing 11, an imaging device 12, aholding unit 13, an imaging device frame 14, a display device frame 15,and an image processing device 17. An example of a commerciallyavailable sparkle measurement apparatus 10 is a Film Sparkle MeasurementApparatus available from Komatsu NTC Ltd.

The housing 11 has a dark room for capturing an image of the display 16a by the imaging device 12. The housing 11 accommodates the imagingdevice 12, the holding unit 13, the imaging-device frame 14, thedisplay-device frame 15, and a display device 16 of an evaluationtarget.

The imaging device 12 is an area camera having, as examples, a lens 18and an imaging element, and captures an image to be displayed on thedisplay 16 a. The imaging device 12 is connected to an image processingdevice 17, and is held by the holding unit 13 such that the lens 18 andthe display 16 a face each other. Image data captured by the imagingdevice 12 is transmitted to the image processing device 17.

The holding unit 13 extends in the vertical direction and holds theimaging device 12 while being fixed to the imaging-device frame 14 atthe lower end. The holding unit 13 holds the imaging device 12 such thata relative distance between the display 16 a and the lens 18 can bechanged by moving the imaging device 12 relative to the display device16 in the vertical direction.

The display device 16 is mounted on a top surface of the display-deviceframe 15 in a state where the display 16 a, on which the film ismounted, faces the imaging device 12. The display-device frame 15supports the display 16 a, on which the film is mounted, such that thesurface of the display 16 a faces the imaging device 12 and serves as ahorizontal surface, and relatively moves the display device 16 withrespect to the imaging device 12 in the vertical direction.

With the sparkle measurement apparatus 10, a pixel size of an imagedisplayed on the display 16 a is adjusted by adjusting a relativedistance between the imaging device 12 and the display 16 a, with theimage being captured per unit pixel (for example, one pixel) of theimaging element of the imaging device 12.

The image processing device 17 performs data processing of image datacaptured by the imaging device 12. Specifically, the image processingdevice 17 determines a standard deviation of luminance of the display 16a from the image data captured by the imaging device 12.

The image processing device 17 of the present embodiment is providedwith: an input unit into which image data captured by the imagecapturing device 12 is input, an image processing unit that performsimage processing on the input image data, and an output unit thatoutputs to a display device, a printing device, or the like, a resultprocessed by the image processing unit.

As the method for adjusting the pixel size of an image to be capturedper unit pixel (for example, one pixel) of the imaging element when animage displayed on the display 16 a is captured by the imaging device12, in addition to the method of changing the relative distance betweenthe imaging device 12 and the display 16 a, in a case where the lens 18included in the imaging device 12 is a zoom lens, a method of changing afocal length of the imaging device 12 may be employed.

Sparkle Evaluation Method

Next, a method of evaluating sparkle of the display 16 a using thesparkle measurement apparatus 10 is described. In this sparkleevaluation method, for convenience of evaluation, the display 16 a, onwhich the film is mounted on the surface thereof, is displayed, inadvance, illuminated uniformly in a single color (green as an example).

Next, an adjusting step is performed to adjust the pixel size of thedisplay 16 a on which the film is mounted, the pixel size being a sizeto be imaged per unit pixel of the imaging element of the imaging device12. In the adjusting step, the relative distance between the imagingdevice 12 and the display 16 a on which the film is mounted is adjusted,according to the number of effective pixels of the imaging element ofthe imaging device 12, to an extent that, in the image captured by theimaging device 12, there is no emission line due to the pixels or thereis no impact on the evaluation of the sparkle of the display 16 a evenif there is an emission line due to the pixels.

Note that the relative distance between the imaging device 12 and thedisplay device 16 is preferably set by taking into account usageconditions of the display device 16 (for example, the relative distancebetween user's eyes and the surface of the display 16 a).

After the adjustment step is performed, a setting step is performed inwhich a measurement area for evaluating the sparkle of the display 16 a,on which the film is mounted, is set. In the setting step, themeasurement area is appropriately set according to, for example, thesize of the display 16 a.

After the adjusting step has been performed, an imaging step isperformed in which the measurement area of the display 16 a, on whichthe film is mounted, is imaged by the imaging device 12. At this time,as an example, at least one of exposure time of the imaging device 12and luminance of all of the pixels of the display 16 a is adjustedwhereby image data as a gray scale image with an 8-bit gradation displayand an average luminance of 170 gradations is obtained. The image datacaptured in the imaging step is input into the image processing device17.

After the imaging step, the image processing device 17 performs acalculation step to determine, by using image data, luminance variationin the measurement area of the display 16 a on which the film ismounted. In this calculation step, the luminance variation is quantifiedas a standard deviation of luminance distribution.

Here, the sparkle of the display 16 a, on which the film is mounted,increases as the luminance variation of the display 16 a, on which thefilm is mounted, becomes greater. Thus, as the value of the standarddeviation of the luminance distribution becomes smaller, the sparkle ofthe display 16 a can be quantitatively evaluated as being smaller. Inaddition, in the adjusting step, the emission line of the display 16 a,on which the film is mounted, is adjusted to an extent that does notaffect the evaluation of the sparkle of the display 16 a, and thereforeluminance unevenness due to an emission line can be suppressed, and thesparkle of the display 16 a can be accurately evaluated. By implementingeach of the steps described above, the standard deviation of theluminance distribution of the display 16 a, on which the film ismounted, can be determined, and the sparkle of the display 16 a can beevaluated by the value.

Examples and Comparative Examples

Hereinafter, the present invention is described in greater detail basedon examples, but the present invention is not limited to these examples.In Examples 1 to 6, an antiglare layer 3 is formed using a phaseseparation structure as a basic structure.

In Comparative Example 1, an antiglare layer is formed, which has a hazevalue that is increased sing commonly used high refractive index beads(such as polystyrene microparticles). In Comparative Example 2, anantiglare layer is formed, which has a haze value that is increasedusing high refractive index nanoparticles (zirconia microparticles). InComparative Example 3, an antiglare layer is formed, which has a hazevalue that is increased using low refractive index nanoparticles (hollowsilica gel particles), with a phase separation structure being a basicstructure. Note that the refractive indexes described in the followingexamples and comparative examples indicate refractive indexes aftercrosslinking (after curing) with regard to a product cured bycrosslinking.

Example 1

A solution was prepared by dissolving 12.5 parts by weight of a methylmethacrylate-3,4-epoxycyclohexyl methyl methacrylate copolymer (CyclomerP available from Daicel-Allnex Ltd., refractive index of 1.51), 4 partsby weight of a cellulose acetate propionate (degree of acetylation=2.5%,degree of propionylation=46%, number average molecular weight of 75000in terms of polystyrene, CAP-482-20 available from Eastman ChemicalCompany, refractive index of 1.49), 150 parts by weight of a nanosilica(refractive index of 1.46)-containing acrylic UV curable compound(UVHC-7800G available from Momentive Performance Materials Japan LLC), 1part by weight of a silicone acrylate (EB1360 available fromDaicel-Allnex Ltd., refractive index of 1.52), 1 part by weight of aphotoinitiator (Irgacure 184 available from BASF Japan Ltd.), and 1 partby weight of a photoinitiator (Irgacure 907 available from BASF JapanLtd.) in a mixed solvent of 81 parts by weight of methyl ethyl ketone,24 parts by weight of 1-butanol, and 13 parts by weight of1-methoxy-2-propanol.

This solution was flow-casted onto a polyethylene terephthalate film(substrate film 2) using a wire bar (#20), and then left in an oven at80° C. for 1 minute to evaporate the solvent, and a coating layer havinga thickness of about 9 μm was formed. The coating layer was irradiatedfor approximately 5 seconds with ultraviolet light using a high-pressuremercury lamp, whereby the coating layer was UV cured. As a result, anantiglare layer 3 was formed, and the antiglare film of Example 1 wasobtained.

Example 2

A solution was prepared by dissolving 15.0 parts by weight of a methylmethacrylate-3,4-epoxycyclohexyl methyl methacrylate copolymer (CyclomerP available from Daicel-Allnex Ltd., refractive index of 1.51), 3 partsby weight of a cellulose acetate propionate (degree of acetylation=2.5%,degree of propionylation=46%, number average molecular weight of 75000in terms of polystyrene, CAP-482-20 available from Eastman ChemicalCompany, refractive index of 1.49), 150 parts by weight of a nanosilica(refractive index of 1.46)-containing acrylic ultraviolet (UV) curablecompound (UVHC-7800G available from Momentive Performance MaterialsJapan LLC), 1 part by weight of a silicone acrylate (EB1360 availablefrom Daicel-Allnex Ltd., refractive index of 1.52), 1 part by weight ofa photoinitiator (Irgacure 184 available from BASF Japan Ltd.), and 1part by weight of a photoinitiator (Irgacure 907 available from BASFJapan Ltd.) in a mixed solvent of 101 parts by weight of methyl ethylketone and 24 parts by weight of 1-butanol.

This solution was flow-casted onto a polyethylene terephthalate film(substrate film 2) using a wire bar (#20), and then left in an oven at80° C. for 1 minute to evaporate the solvent, and a coating layer havinga thickness of about 9 μm was formed. The coating layer was irradiatedfor approximately 5 seconds with ultraviolet light using a high-pressuremercury lamp, whereby the coating layer was UV cured. As a result, anantiglare layer 3 was formed, and the antiglare film of Example 2 wasobtained.

Example 3

A solution was prepared by dissolving 12.5 parts by weight of a methylmethacrylate-3,4-epoxycyclohexyl methyl methacrylate copolymer (CyclomerP available from Daicel-Allnex Ltd., refractive index of 1.51), 4 partsby weight of a cellulose acetate propionate (degree of acetylation=2.5%,degree of propionylation=46%, number average molecular weight of 75000in terms of polystyrene, CAP-482-20 available from Eastman ChemicalCompany, refractive index of 1.49), 209.3 parts by weight of ananosilica (refractive index of 1.46)-containing acrylic UV curablecompound (HP-1004 available from JGC Catalysts and Chemicals Ltd.), 1part by weight of a silicone acrylate (EB1360 available fromDaicel-Allnex Ltd., refractive index of 1.52), 1 part by weight of aphotoinitiator (Irgacure 184 available from BASF Japan Ltd.), and 1 partby weight of a photoinitiator (Irgacure 907 available from BASF JapanLtd.) in a mixed solvent of 31 parts by weight of methyl ethyl ketone,25 parts by weight of 1-butanol, and 12 parts by weight of1-methoxy-2-propanol.

This solution was flow-casted onto a polyethylene terephthalate film(substrate film 2) using a wire bar (#20), and then left in an oven at80° C. for 1 minute to evaporate the solvent, and a coating layer havinga thickness of about 9 μm was formed. The coating layer was irradiatedfor approximately 5 seconds with ultraviolet light using a high-pressuremercury lamp, whereby the coating layer was UV cured. As a result, theantiglare layer 3 was formed, and the antiglare film of Example 3 wasobtained.

Example 4

A solution was prepared by dissolving 34.2 parts by weight of an acrylicpolymer (8KX-078 available from Taisei Fine Chemical Co., Ltd.), 20parts by weight of a urethane modified copolyester resin (UR-3200available from Toyobo Co., Ltd.), 131.7 parts by weight of a nanosilica(refractive index of 1.46)-containing acrylic UV curable compound(UVHC-7800G available from Momentive Performance Materials Japan LLC), 1part by weight of a silicone acrylate (EB1360 available fromDaicel-Allnex Ltd., refractive index of 1.52), 1 part by weight of aphotoinitiator (Irgacure 184 available from BASF Japan Ltd.), and 1 partby weight of a photoinitiator (Irgacure 907 available from BASF Japanltd.) in 213 parts by weight of methyl ethyl ketone.

This solution was flow-casted onto a polyethylene terephthalate film(substrate film 2) using a wire bar (#16), and then left in an oven at80° C. for 1 minute to evaporate the solvent, and a coating layer havinga thickness of about 9 μm was formed. The coating layer was irradiatedfor approximately 5 seconds with ultraviolet light using a high-pressuremercury lamp, whereby the coating layer was UV cured. As a result, theantiglare layer 3 was formed, and the antiglare film of Example 4 wasobtained.

Example 5

A solution was prepared by dissolving 34.2 parts by weight of an acrylicpolymer (8KX-078 available from Taisei Fine Chemical Co., Ltd.), 20parts by weight of a urethane modified copolyester resin (UR-3200available from Toyobo Co., Ltd.), 131.7 parts by weight of a nanosilica(refractive index of 1.46)-containing acrylic UV curable compound(UVHC-7800G available from Momentive Performance Materials Japan LLC), 5parts by weight of a silicone acrylate (EB1360 available fromDaicel-Allnex Ltd., refractive index of 1.52), 1 part by weight of aphotoinitiator (Irgacure 184 available from BASF Japan Ltd.), and 1 partby weight of a photoinitiator (Irgacure 907 available from BASF Japanltd.) in 213 parts by weight of methyl ethyl ketone.

This solution was flow-casted onto a polyethylene terephthalate film(substrate film 2) using a wire bar (#16), and then left in an oven at80° C. for 1 minute to evaporate the solvent, and a coating layer havinga thickness of about 9 μm was formed. The coating layer was irradiatedfor approximately 5 seconds with ultraviolet light using a high-pressuremercury lamp, whereby the coating layer was UV cured. As a result, theantiglare layer 3 was formed, and the antiglare film of Example 5 wasobtained.

Example 6

A solution was prepared by dissolving 47.5 parts by weight of a methylmethacrylate-3,4-epoxycyclohexyl methyl methacrylate copolymer (CyclomerP available from Daicel-Allnex Ltd., refractive index of 1.51), 1.5parts by weight of a cellulose acetate propionate (degree ofacetylation=2.5%, degree of propionylation=46%, number average molecularweight of 75000 in terms of polystyrene, CAP-482-20 available fromEastman Chemical Company, refractive index of 1.49), 79.5 parts byweight of a urethane acrylate (UA-53H available from Shin-NakamuraChemical Co., Ltd.), 1 part by weight of a photoinitiator (Irgacure 184available from BASF Japan Ltd.), and 1 part by weight of aphotoinitiator (Irgacure 907 available from BASF Japan Ltd.) in a mixedsolvent of 175 parts by weight of methyl ethyl ketone, 28 parts byweight of 1-butanol, and 2 parts by weight of 1-methoxy-2-propanol.

This solution was flow-casted onto a polyethylene terephthalate film(substrate film 2) using a wire bar (#14), and then left in an oven at80° C. for 1 minute to evaporate the solvent, and a coating layer havinga thickness of about 6 μm was formed. The coating layer was irradiatedfor approximately 5 seconds with ultraviolet light using a high-pressuremercury lamp, whereby the coating layer was UV cured. As a result, theantiglare layer 3 was formed, and the antiglare film of Example 6 wasobtained.

Comparative Example 1

A solution was prepared by dissolving 39 parts by weight of a urethaneacrylate (AU-230 available from Tokushiki Co., Ltd., refractive index of1.52), 15.7 parts by weight of a silicon-based hard coat material(AS-201S available from Tokushiki Co., Ltd.), 0.3 parts by weight ofPMMA beads (SSX-115 available from Sekisui Chemical Co., Ltd.,refractive index of 1.50), and 6.1 parts by weight of crosslinkedstyrene beads (SX-130H, available from Soken Chemical & Engineering Co.,Ltd., refractive index of 1.59) in 38 parts by weight of methyl ethylketone.

This solution was flow-casted onto a polyethylene terephthalate film(substrate film) using a wire bar (#14), and then left in an oven at100° C. for 1 minute to evaporate the solvent, and a coating layerhaving a thickness of about 6 μm was formed. The coating layer wasirradiated for approximately 5 seconds with ultraviolet light using ahigh-pressure mercury lamp, whereby the coating layer was UV cured. As aresult, an antiglare layer was formed, and the antiglare film ofComparative Example 1 was obtained.

Comparative Example 2

A solution was prepared by dissolving 50 parts by weight of adipentaerythritol hexaacrylate (DPHA available from Daicel-Allnex Ltd.,refractive index of 1.52), 50 parts by weight of a pentaerythritoltetraacrylate (PETRA available from Daicel-Allnex Ltd., refractive indexof 1.52), 100 parts by weight of a zirconia microparticle (refractiveindex of approximately 2.0) dispersion (Lioduras TYZ available from ToyoInk Co., Ltd.), 2 parts by weight of a photoinitiator (Irgacure 184available from BASF Japan Ltd.), and 1 part by weight of aphotoinitiator (Irgacure 907 available from BASF Japan Ltd.) in a mixedsolvent of 116 parts by weight of methyl ethyl ketone, 19 parts byweight of 1-butanol, and 58 parts by weight of 1-methoxy-2-propanol.

This solution was flow-casted onto a polyethylene terephthalate film(substrate film) using a wire bar (#14), and then left in an oven at 80°C. for 1 minute to evaporate the solvent, and a coating layer having athickness of about 6 μm was formed. The coating layer was irradiated forapproximately 5 seconds with ultraviolet light using a high-pressuremercury lamp, whereby the coating layer was UV cured. As a result, anantiglare layer was formed, and the antiglare film of ComparativeExample 2 was obtained.

Comparative Example 3

A solution was prepared by dissolving 12.5 parts by weight of a methylmethacrylate-3,4-epoxycyclohexyl methyl methacrylate copolymer (CyclomerP available from Daicel-Allnex Ltd., refractive index of 1.51), 4 partsby weight of a cellulose acetate propionate (degree of acetylation=2.5%,degree of propionylation=46%, number average molecular weight of 75000in terms of polystyrene, CAP-482-20 available from Eastman ChemicalCompany, refractive index of 1.49), 125 parts by weight of adipentaerythritol hexaacrylate (DPHA available from Daicel-Allnex Ltd.),1 part by weight of a silicone acrylate (EB1360 available fromDaicel-Allnex Ltd., refractive index of 1.52), 75 parts by weight of ahollow silica gel (Thrulya available from JGC Catalysts and ChemicalsLtd., refractive index of 1.25), 1 part by weight of a photoinitiator(Irgacure 184 available from BASF Japan Ltd.), and 1 part by weight of aphotoinitiator (Irgacure 907 available from BASF Japan Ltd.) in a mixedsolvent of 56 parts by weight of methyl ethyl ketone, 11 parts by weightof 1-butanol, and 10 parts by weight of 1-methoxy-2-propanol.

This solution was flow-casted onto a polyethylene terephthalate film(substrate film) using a wire bar (#20), and then left in an oven at 80°C. for 1 minute to evaporate the solvent, and a coating layer having athickness of about 9 μm was formed. The coating layer was irradiated forapproximately 5 seconds with ultraviolet light using a high-pressuremercury lamp, whereby the coating layer was UV cured. As a result, anantiglare layer was formed, and the antiglare film of ComparativeExample 3 was obtained.

Next, items below were measured and evaluated for each antiglare film ofExamples 1 to 6 and Comparative Examples 1 to 3. The adhesive layer wasomitted for measurements of haze and total light transmittance, 60degree gloss, a surface structure, and transmission hue (a*, b*).

Haze and Total Light Transmittance

Haze was measured in accordance with JIS K7136 using a haze meter(NDH-5000W available from Nippon Denshoku Industries Co., Ltd.). Thehaze was measured, with the surface having a concave-convex structure ofan antiglare layer being disposed on a light receiver side. The internalhaze was measured by affixing, via a transparent adhesive layer, asmooth transparent film to the surface of the antiglare layer having theconcavo-convex structure.

60 Degree Gloss

60 degree gloss was measured at an angle of 60° using a gloss meter(“IG-320” available from Horiba, Ltd.) in accordance with JIS K7105.

Surface Structure

Center-line average surface-roughness (Ra) and mean spacing betweenpeaks (Sm) were measured in accordance with JIS B0601 using a contacttype surface roughness meter (Surfcom 570A available from Tokyo SeimitsuCo., Ltd.) under the following conditions: scan range of 3 mm, 2 timesof scanning.

Transmission Hue (a*, b*)

The transmission hue was measured using a spectrophotometer (U-3010available from Hitachi High-Tech Science Corporation) in accordance withJIS Z8781.

Standard Deviation (Sparkle Value) of Luminance Distribution of Display

A smartphone (“Galaxy S4”, available from Samsung Electronics Co., Ltd.)was used as the display device 16, and the antiglare film of each samplewas affixed to the surface of the display 16 a using an adhesive layer(optical glue). Standard deviation (sparkle σ: sparkle value) ofluminance distribution of the display 16 a was measured through theantiglare film of each sample using the film sparkle measurementapparatus 10 available from Komatsu NTC Ltd. When the measurement wasperformed, at least one of the exposure time of the imaging device 12and the luminance of all of the pixels of the display 16 a was adjustedsuch that image data was obtained as a gray scale image with an 8-bitgradation display and an average luminance of 170 gradations.

The measurement results are shown in Table 1.

TABLE 1 Example Example Example Example Example Example ComparativeComparative Comparative Item 1 2 3 4 5 6 Example 1 Example 2 Example 3Haze (%) 79.5 67.8 87.9 83.2 91.49 72.2 83.0 78.3 80.3 Internal haze 6.03.3 7.0 7.5 13 6.8 59.4 67.4 79.8 (%) Total Light 94.0 94.5 92.0 97.399.2 96.3 97.4 94.5 94.3 Transmittance (%) 60 degree gloss 3 8 2 2 1 4.012 92 60 (%) Ra (μm) 0.88 0.61 0.44 0.49 0.50 0.32 0.43 0.04 0.15 Sm(μm) 46.3 45.7 31.5 36.1 35.6 56.4 306.7 1.5 205.6 a* −0.22 −0.17 0.070.69 0.45 0.15 2.20 2.85 3.32 b* 1.57 2.00 2.48 7.41 4.26 2.32 16.2215.79 10.94 Sparkle σ 4.49 9.01 4.43 5.21 4.34 7.64 4.71 4.20 4.58(Standard deviation of luminance distribution)

As shown in Table 1, in the antiglare layers 3 of Examples 1 to 6, thehaze values were set to a value in a range from 67.8% to 91.49%, and theinternal haze values were set to a value in a range from 3.3% to 13.0%,which are lower than the internal haze values of Comparative Examples 1to 3. Furthermore, the values of the 60 degree gloss (%) of theantiglare layers 3 of Examples 1 to 6 are more sufficiently suppressedthan the values of the 60 degree gloss (%) of the antiglare layers ofComparative Examples 1 to 3. Additionally, in each of the antiglarefilms of Examples 1 to 6 and Comparative Examples 1 to 3, the sparklevalue (sparkle σ) of the display 16 a was suppressed to a value in arange from 0 to 10.

As shown in Table 1, it was ascertained that, in comparison toComparative Examples 1 to 3, Examples 1 to 6 exhibit, at an equivalentlevel to that of Comparative Examples 1 to 3, favorable antiglareproperty and can effectively suppress the b* value and preventcoloration of the antiglare film while suppressing the sparkle value ofthe display 16 a.

This is because in Examples 1 to 6, the concave-convex structure of thesurface of the antiglare layer 3 is formed basically by a phaseseparation structure, and the refractive index difference between theresins that are combined so as to form the phase separation structure inthe antiglare layer 3 is suppressed (here, the refractive index valuesare set to be equal), hence it is considered that even though theantiglare layer 3 has a relatively high haze value, scattering oftransmitted light in a wide angle within the antiglare layer 3 isprevented.

In addition, it is considered that, with the antiglare layers 3 ofExample 1 to 5 containing microparticles (nano silica particles), therefractive index value of the microparticles and the refractive indexvalue of the resin that forms the phase separation structure areapproximately equivalent (0.07 or less), scattering of transmitted lightin a wide angle is prevented, and coloration of the antiglare film 1 isprevented.

Furthermore, based on the trends of characteristics in Examples 1 to 6,and examination separately conducted by the inventors of the presentapplication, it is considered that the same effects as those of Examples1 to 6 would be achieved even for a case in which the haze value is setto a value in a range from 60% to less than 67.8%, or in a range from avalue greater than 91.49% to 95% or less, the internal haze value is setto a value in a range from 0.5% to less than 3.3%, or in a range from avalue greater than 13.0% to 15.0% or less, and the sparkle value is setto a value in a range from 0 to less than 4.34, or in a range from 9.01to 10 or less.

In comparison to Examples 1 to 6, Comparative Examples 1 to 3 were foundto have relatively large internal haze values and large b* values. InComparative Example 1, it is considered that due to the refractive indexdifference between the matrix resin and the beads that are added in arelatively large amount to the matrix resin in the antiglare layer,there are many occurrences of scattering in a wide angle of lowwavelength light (blue light), which is easily scattered, of thetransmitted light, and the antiglare film is colored so as to be tingedwith a yellowish color.

In Comparative Example 2, the internal haze value is increased byadding, to the antiglare layer, microparticles (nanoparticles) having arelatively high refractive index, and in Comparative Example 3, theinternal haze value is increased by adding microparticles(nanoparticles) having a lower refractive index than that of theantiglare layer having a phase separation structure.

However, in Comparative Examples 2 and 3, the refractive indexdifference between the matrix resin and the microparticles is relativelylarge, and, it is considered that, similarly to Comparative Example 1,there are many occurrences of scattering in a wide angle of lowtransmitted light, and the antiglare film is colored so as to be tingedwith a yellowish color.

Furthermore, from the results of Examples 1 to 5 and Comparative Example3, it was found that even for a case in which the antiglare layer isformed using a phase separation structure as a basic structure, whenscattering of transmitted light in a wide angle occurs by a relativelylarge refractive index difference between the matrix resin and themicroparticles in the antiglare layer, the antiglare film may becolored.

Thus, when adding microparticles to the antiglare layer, it is desirableto suppress the refractive index difference between the microparticlesand the resin or matrix resin that forms the phase separation structureto prevent coloration of the antiglare film.

The present invention is not limited to the embodiments described above,and changes, additions, or deletions can be made to the configurationsor methods therefor without departing from the scope of the presentinvention. For example, the microparticles of the second embodiment maybe dispersed in the antiglare layer of the first embodiment or the thirdembodiment.

REFERENCE SIGNS LIST

-   1 Antiglare film-   3, 33 Antiglare layer-   16 a Display

1. An antiglare film comprising an antiglare layer having a haze valuein a range from 60% to 95%, an internal haze value in a range from 0.5%to 15.0%, and a standard deviation of luminance distribution of adisplay in a state, where the antiglare film is mounted on a surface ofthe display, in a range of from 0 to
 10. 2. The antiglare film accordingto claim 1, wherein b* value in Pa*b* color system is a value in a rangefrom 0 to
 10. 3. The antiglare film according to claim 1, wherein theantiglare layer comprises a plurality of resin components and has aco-continuous phase structure formed by phase separation of theplurality of resin components.
 4. The antiglare film according to claim1, wherein the antiglare layer comprises a matrix resin and a pluralityof microparticles dispersed in the matrix resin, and a refractive indexdifference between the microparticles and the matrix resin is a value ina range from 0 to 0.07.
 5. The antiglare film according to claim 4,wherein a ratio G2/G1 of a weight G1 of the matrix resin of theantiglare layer to a total weight G2 of the plurality of microparticlesincluded in the antiglare layer is a value a range from 0.07 to 0.20. 6.The antiglare film according to claim 2, wherein the antiglare layercomprises a plurality of resin components and has a co-continuous phasestructure formed by phase separation of the plurality of resincomponents.
 7. The antiglare film according to claim 2, wherein theantiglare layer comprises a matrix resin and a plurality ofmicroparticles dispersed in the matrix resin, and a refractive indexdifference between the microparticles and the matrix resin is a value ina range from 0 to 0.07.